[yifehuan]

Motivation

The gfx1250 single-launch step kernel (DeepSeek-V4.1, PR #3109) does not build with FlyDSL 0.5: tracing fails with

'llvm.inttoptr' op operand #0 type from a different MLIRContext than this operation

The step kernel sets two trace-time slots while it traces -- the poll-timeout counter pointer (device.TOFLAG) and the stamp hook (stamps.HOOK) -- and clears them when its body ends. They are module-level [None] lists. FlyDSL 0.5 traces every kernel in its own MLIRContext, and a launcher that traces several ranks' kernels in parallel threads then hands one thread's IR value to another thread's trace. FlyDSL 0.4 used one context, which hid the sharing.

Change

device.TraceSlot: one trace-time value private to the tracing thread, with the same slot[0] interface. TOFLAG and HOOK use it. Serial tracing (FlyDSL 0.4) is unchanged.

Validation

On gfx1250 (CT10, 4 GPUs), the single-launch fixture (40 target + 3 draft layers, TP4, 6 rows) with the same thread-local slots:

• FlyDSL 0.5.0 (the gfx1250-atom-k3-20261111 image's bundled FlyDSL): builds, runs all iterations, zero poll timeouts.
• Logits vs the FlyDSL 0.4.1 run: relative L2 1.1e-4 (the kernel's known atomic-order nondeterminism), top-1 6/6.

Not covered here: the kernel's performance under FlyDSL 0.5 (the 0.5.0 run's median step was slower than 0.4.1 in this fixture; to be investigated separately).

🤖 Generated with Claude Code

[github-actions]

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[valar-cop]

LGTM

ci green.